Synthesis, spectral, thermal, optical dispersion and dielectric properties of nanocrystalline dimer complex (PEPyr–diCd) thin films as novel organic semiconductor

Abstract

Dimer complex PEPyr–diCd (5a) has been prepared by reacting CdCl2⋅2.5H2O with 1,1′-bis(diphenylphosphino)ethyl-6-methyl-3-(pyridin-2-yl)-1,4-dihydro-pyridazine tungsten tetracarbonyl PEPyr (4a) as bipyridine ligand. The structural properties of PEPyr–diCd complex were characterized on the basis of elemental analysis (EA), Fourier transform infrared spectra, fast atom bombardment-mass spectrometry, thermogravimetric/differential thermal analysis, and 1H nuclear magnetic resonance spectroscopy. The crystal is orthorhombic, space group Pbca. Cd(II) metal in PEPyr–diCd organic semiconductor complex coordinated with two N of the PEPyr and three Cl − (one terminal and two bridging). The micro-structural properties of the films were studied via X-ray diffraction, and scanning electron microscopy. The as-deposited films were annealed in air for 1 h at 150, 200, and 250 ∘C. An average transmittance ≥ 70% for PEPyr–diCd complex at higher wavelength ≥ 800 nm was observed. In UV spectrum, the transmittance increases followed by a sharp decrease at wavelength 700–750 nm within visible range. The results of the absorption coefficient were determined to find the binding energy (E B ) of PEPyr–diCd organic semiconductor complex as 0.242 and 0.47 eV, respectively. Refractive index (n) and absorption index (K) of PEPyr–diCd complex were calculated. Moreover, the dispersion parameters such as dispersion energy, oscillator energy, dielectric constant, and dissipation factor were determined. The oxidation of the imino-phosphine derivatives were examined using cyclic voltammetry in methylene chloride solvent. The cyclic voltammogram of PEPyr–diCd (5a) organic semiconductor appears to have two quasi-reversible oxidations at 543 and 441 mV. The obtained results indicate that the PEPyr–diCd organic semiconductor thin film is a good candidate in optoelectronic devices based on its band gap and dispersion parameters.